CMTM6 and PD-L1 coexpression is associated with an active immune microenvironment and a favorable prognosis in colorectal cancer

Prognostic value of CMTM6 protein in hepatocellular carcinoma involving the regulation of the immune microenvironment

There have been notable irregularities in CMTM6 expression observed in hepatocellular carcinoma (HCC), with an evident correlation between CMTM6 dysregulation and patient prognosis. The cell cycle progression came to a halt at the G2/M phase. In-depth RNA-sequencing analysis of CMTM6 knockdown Hep3B cells revealed that the most prominent effect of CMTM6 perturbation was on the expression of CXCL8, a chemokine involved in immune responses, particularly through the interleukin-17F (IL-17F) signaling pathway. By carefully examining the RNA-sequencing data obtained from CMTM6 knockdown Hep3B cells and cross-referencing it with the TCGA-LIHC database, we were able to discern that CMTM6 and programmed death-ligand 1 (PD-L1) collaboratively partake in immune regulation within T cells. Furthermore, CMTM6 exerted an influential role in modulating the infiltration of CD4+ and CD8+ T cells in the HCC microenvironment, thereby impacting the overall immune response. Our investigation found that HCC cases characterized by an elevated co-expression of CMTM6 and PD-L1, along with augmented CD4+ T cell infiltration, demonstrated comparatively longer overall and progression-free survival rates when contrasted with those displaying lower CD4+ T cell infiltration.

CMTM6 promotes hepatocellular carcinoma progression through stabilizing β-catenin

CMTM6, a regulator of PD-L1 stability, has been implicated in the development of various cancers. However, the expression and role of CMTM6 in hepatocellular carcinoma (HCC) remains controversial. Our study revealed a negative correlation between CMTM6 expression and HCC prognosis through bioinformatics analysis and immunofluorescence staining. CMTM6 expression was also positively associated with alpha-fetoprotein (AFP) levels, supporting its potential as a prognostic marker for HCC. Using Cmtm6 knockout mice, we found that Cmtm6 deficiency inhibited HCC formation and cell proliferation in primary liver cancer models induced by DEN and DEN/CCl4. In HCC cell lines, CMTM6 promoted cell proliferation and interacted with β-catenin, stabilizing it by preventing ubiquitination. In conclusion, our study suggested that CMTM6 upregulation promotes HCC cell proliferation through the β-catenin pathway, making it a potential therapeutic target for HCC treatment.

Immunotherapy and radiotherapy for older patients with locally advanced rectal cancer unfit for surgery or decline surgery: a practical proposal by the International Geriatric Radiotherapy Group

The standard of care for locally advanced rectal cancer is total neoadjuvant therapy followed by surgical resection. Current evidence suggests that selected patients may be able to delay or avoid surgery without affecting survival rates if they achieve a complete clinical response (CCR). However, for older cancer patients who are too frail for surgery or decline the surgical procedure, local recurrence may lead to a deterioration of patient quality of life. Thus, for clinicians, a treatment algorithm which is well tolerated and may improve CCR in older and frail patients with rectal cancer may improve the potential for prolonged remission and potential cure. Recently, immunotherapy with check point inhibitors (CPI) is a promising treatment in selected patients with high expression of program death ligands receptor 1 (PD- L1). Radiotherapy may enhance PD-L1 expression in rectal cancer and may improve response rate to immunotherapy. We propose an algorithm combining immunotherapy and radiotherapy for older patients with locally advanced rectal cancer who are too frail for surgery or who decline surgery.

Clinical implications of PD-L1 expression and pathway-related molecular subtypes in advanced Asian colorectal cancer patients

The expression level of PD-L1 does not accurately predict the prognosis of advanced colorectal cancer (CRC) patients, but it still reflects the tumor microenvironment to some extent. By stratifying PD-L1 status, gene subtypes in PD-L1 positivity-related pathological pathways were analyzed for their relationship to MSI or TMB to provide more individualized treatment options for CRCs. A total of 752 advanced CRCs were included, and their genomic variance was measured by a targeted next generation sequencing panel in this study. MSI and TMB were both measured by NGS, while PD-L1 expression level was measured using the PD-L1 colon 22C3 pharmDx kit. We found RTK/RAS pathway was positively related to high PD-L1 expression, with BRAF V600E and most KRAS mutations (G12 and G13) subtypes showing a significant correlation. Conversely, the Wnt and p53 pathways were negatively related to high PD-L1 expression, with APC C-terminal alterations and other non-inactivation mutations in TP53 making a primary contribution with significant statistical significance. Major subtypes showing a significantly higher proportion of TMB-H or MSI-H were irrespective of PD-L1 status. These findings demonstrate pathological pathways associated with high PD-L1 expression, suggesting that pathway-induced oncogenic constructive PD-L1 upregulation may be the reason for the corresponding patients' primary resistance to immune checkpoint inhibitors (ICIs), rather than a lack of pre-existing immune responses.

Elevated enteric putrescine suppresses differentiation of intestinal germinal center B cells

The dysregulation of B cell maturation and putrescine metabolism has been implicated in various diseases. However, the causal relationship between them and the underlying mechanisms remain unclear. In this study, we investigated the impact of exogenous putrescine on B cell differentiation in the intestinal microenvironment. Our results demonstrated that administration of exogenous putrescine significantly impaired the proportion of germinal center B (GC B) cells in Peyer's patches (PPs) and lamina propria. Through integration of bulk RNA sequencing and single-cell RNA sequencing (scRNA-seq), we identified putrescine-mediated changes in gene drivers, including those involved in the B cell receptor (BCR) signaling pathway and fatty acid oxidation. Furthermore, putrescine drinking disrupted T-B cell interactions and increased reactive oxygen species (ROS) production in B cells. In vitro activation of B cells confirmed the direct suppression of putrescine on GC B cells differentiation and ROS production. Additionally, we explored the Pearson correlations between putrescine biosynthesis activity and B cell infiltration in pan-cancers, revealing negative correlations in colon adenocarcinoma, stomach adenocarcinoma, and lung adenocarcinoma, but positive correlations in liver hepatocellular carcinoma, and breast invasive carcinoma. Our findings provided novel insights into the suppressive effects of elevated enteric putrescine on intestinal B cells differentiation and highlighted the complex and distinctive immunoregulatory role of putrescine in different microenvironments. These findings expand our understanding of the role of polyamines in B cell immunometabolism and related diseases.

CMTM 6 promotes the development of thyroid cancer by inhibiting NIS activity through activating the MAPK signaling pathway

Thyroid cancer is the most common type of endocrine cancer. Chemokine-like factor (CKLF)-like MARVEL transmembrane domain containing 6 (CMTM6) is recognized as one of its potential immunotherapy targets. The purpose of this study was to investigate the role and molecular mechanism of CMTM6 in regulating the development of thyroid cancer cells. In this study, expression levels of CMTM6 and the sodium/iodide symporter (NIS) were detected by qRT-PCR. Additionally, colony formation assay and flow cytometry were used to detect cell proliferation and apoptosis, while expression levels of various proteins were assessed using Western blotting. Further, the apoptosis and invasion capacity of cells were investigated by scratch and transwell experiments. Finally, the effect of CMTM6 on the epithelial-mesenchymal transition (EMT) of thyroid cancer cells was determined by immunofluorescence assay, which measured the expression levels of epithelial and mesenchymal phenotypic markers. The results of qRT-PCR experiments showed that CMTM6 was highly expressed in thyroid cancer tissues and cells. In addition, knockdown of CMTM6 expression significantly increased NIS expression. Function experiments demonstrated that small interfering (si)-CMTM6 treatment inhibited the proliferation, migration, invasion, and EMT of thyroid cancer cells, while promoting apoptosis of FTC133 cells. Furthermore, mechanistic studies showed that mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) phosphorylation were inhibited by si-CMTM6, as demonstrated by Western blot experiments. In conclusion, our findings demonstrated the role of CMTM6 in the metastasis of thyroid cancer. Briefly, CMTM6 exerts its tumor-promoting effect through the MAPK signaling pathway and could potentially be used as a valuable biomarker for thyroid cancer diagnosis and prognosis.

Optimization of cancer immunotherapy on the basis of programmed death ligand-1 distribution and function

Programmed cell death protein-1 (PD-1)/programmed death ligand-1 (PD-L1) immune checkpoint blockade as a breakthrough in cancer immunotherapy has shown unprecedented positive outcomes in the clinic. However, the overall effectiveness of PD-L1 antibody is less than expected. An increasing number of studies have demonstrated that PD-L1 is widely distributed and expressed not only on the cell membrane but also on the inside of the cells as well as on the extracellular vesicles secreted by tumour cells. Both endogenous and exogenous PD-L1 play significant roles in influencing the therapeutic effect of anti-tumour immunity. Herein, we mainly focused on the distribution and function of PD-L1 and further summarized the potential targeted therapeutic strategies. More importantly, in addition to taking the overall expression abundance of PD-L1 as a predictive indicator for selecting corresponding PD-1/PD-L1 monoclonal antibodies (mAbs), we also proposed that personalized combination therapies based on the different distribution of PD-L1 are worth attention to achieve more efficient and effective therapeutic outcomes in cancer patients. LINKED ARTICLES: This article is part of a themed issue on Cancer Microenvironment and Pharmacological Interventions. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.2/issuetoc.

Molecular and immunological characteristics of patients with CMTM6 low expression colorectal cancer

CKLF-like MARVEL transmembrane domain-containing 6 (CMTM6), a regulator of programmed cell death ligand 1 (PD-L1), has attracted extensive attention due to its role in tumors. However, research on the expression of CMTM6 in colorectal cancer (CRC) and its relationship with PD-L1 expression and immune cell infiltration is limited. We used The Cancer Genome Atlas database to mine and analyze data from patients with CRC using bioinformatics methods. We investigated the expression of CMTM6 in CRC and its relationship with PD-L1 expression and immune cell infiltration. Immunohistochemistry and PCR were performed to detect CMTM6 and PD-L1 expression in CRC tissues. Differential gene expression analysis was performed using the edgeR package in R and immune cell infiltration analysis was performed using the ssGSEA algorithm. Additionally, GO and KEGG enrichment analyses were conducted to identify the biological processes and pathways associated with low CMTM6 expression. Our study found that CMTM6 expression was significantly upregulated in CRC tissues compared to that in adjacent normal tissues. Patients with high CMTM6 expression exhibited significantly increased levels of PD-L1 expression and higher levels of tumor-infiltrating immune cells compared to patients with low CMTM6 expression. GO and KEGG analyses suggested that CMTM6 may be involved in multiple immune regulatory pathways in CRC.

Clinicopathological and prognostic significance of PD-L1 expression in colon adenocarcinoma tumor budding

OBJECTIVE

In this study, we investigated the relationship between programmed cell death ligand 1 (PD-L1) and programmed cell death protein 1 (PD-1) expression in colon adenocarcinoma tumor budding.

METHODS

This study included 122 patients with colon adenocarcinomas. The largest sample of formaldehyde-fixed paraffin-embedded tumor tissues was selected for analysis. Expression of membranous PD-L1 (clone 22C3) and the Combined Positive Score (CPS) in tumor tissues was calculated and graded according to the percentages of peritumoral and intratumoral tumor cells (0 %, 1 %, 1-5 %, >5 %). The effects of these factors on the prognosis were analyzed.

RESULTS

Tumor budding was associated with adverse clinicopathological features and poor overall survival. PD-L1 (CPS%) peritumoral tumor budding (1 %/<1 %) was statistically significant in the univariate model (p = 0.004). Age, organ metastases (liver, lung, liver, lung, and peritoneum), and metastases were statistically significant in the multivariate model (p = 0.001, p = 0.004, p = 0.001, p = 0.002, p = 0.004, and p = 0.032, respectively). PD-L1 positive staining was mostly observed around the tumor and during tumor budding. PD-L1 peritumoral tumor budding rates and patients' survival rates differed significantly (log-rank = 12.07, p = 0.007).

CONCLUSION

We found that patients with PD-L1 (CPS%) > 1 % in tumor budding had a shortened life expectancy and demonstrated the importance of including tumor budding areas in the samples used for biomarker evaluation. We previously reported that PD-L1 expression in tumor budding is associated with more aggressive cancer biology and poor survival, although overall survival is of limited statistical significance.

Prognostic value of primary tumor location in colorectal cancer: an updated meta-analysis

The clinical, histological, and molecular differences between right-sided colon cancer (RCC) and left-sided colon cancer (RCC) have received considerable attention. Over the past decade, many articles have been published concerning the association between primary tumor location (PTL) of colorectal cancer and survival outcomes. Therefore, there is a growing need for an updated meta-analysis integrating the outcomes of recent studies to determine the prognostic role of right vs left-sidedness of PTL in patients with colorectal cancer. We conducted a comprehensive database review using PubMed, SCOPUS, and Cochrane library databases from February 2016 to March 2023 for prospective or retrospective studies reporting data on overall survival (OS) and cancer-specific survival (CSS) of RCC compared with LCC. A total of 60 cohort studies comprising 1,494,445 patients were included in the meta-analysis. We demonstrated that RCC is associated with a significantly increased risk of death compared with LCC by 25% (hazard ratio (HR), 1.25; 95% confidence interval (CI), 1.19-1.31; I2 = 78.4%; Z = 43.68). Results showed that patients with RCC have a worse OS compared with LCC only in advanced stages (Stage III: HR, 1.275; 95% CI 1.16-1.4; P = 0.0002; I2 = 85.8%; Stage IV: HR, 1.34; 95% CI 1.25-1.44; P < 0.0001; I2 = 69.2%) but not in primary stages (Stage I/II: HR, 1.275; 95% CI 1.16-1.4; P = 0.0002; I2 = 85.8%). Moreover, a meta-analysis of 13 studies including 812,644 patients revealed that there is no significant difference in CSS between RCC and LCC (HR, 1.121; 95% CI 0.97-1.3; P = 0.112). Findings from the present meta-analysis highlight the importance of PTL in clinical decision-making for patients with CRC, especially in advanced stages. We provide further evidence supporting the hypothesis that RCC and LCC are distinct disease entities that should be managed differently.

Integrated analysis of single cell and bulk RNA sequencing identifies CTHRC1+ INHBA+ CAF as drivers of colorectal cancer progression

Cancer-associated fibroblasts (CAFs) are a key component of the tumor microenvironment and a critical factor in the progression of colorectal cancer (CRC). The aim of this study was to screen for CAFs specific genes that could serve as promising therapeutic targets for CRC patients. Our findings showed a significant increase in the proportion of fibroblasts in CRC tissues, and a high proportion of fibroblasts was associated with immune escape and poor prognosis in CRC. Collagen triple helix repeat containing 1 (CTHRC1) and inhibin subunit beta A (INHBA) were identified as key genes in the progression of CRC, primarily expressed in CAFs and significantly upregulated in CRC tissues. We defined CTHRC1 and INHBA as cancer-associated fibroblast-related genes (CAFRGs), which were associated with poor prognosis in CRC and macrophage polarization. CAFRGs promoted immune escape and metastasis in CRC and were good predictors of immune therapy response. Drug sensitivity analysis showed that the high expression group of CAFRGs was sensitive to 15 chemotherapy drugs, while the low expression group was sensitive to only 3. Clustering of fibroblasts in the tumor revealed that CTHRC1+ INHBA+ CAF was a poor prognostic factor in CRC and was associated with extracellular matrix remodeling and immune regulation. In conclusion, our study provides new theoretical basis for effective treatment strategies and therapeutic targets for CRC.

Integration of liquid biopsy and immunotherapy: opening a new era in colorectal cancer treatment

Immunotherapy has revolutionized the conventional treatment approaches for colorectal cancer (CRC), offering new therapeutic prospects for patients. Liquid biopsy has shown significant potential in early screening, diagnosis, and postoperative monitoring by analyzing circulating tumor cells (CTC) and circulating tumor DNA (ctDNA). In the era of immunotherapy, liquid biopsy provides additional possibilities for guiding immune-based treatments. Emerging technologies such as mass spectrometry-based detection of neoantigens and flow cytometry-based T cell sorting offer new tools for liquid biopsy, aiming to optimize immune therapy strategies. The integration of liquid biopsy with immunotherapy holds promise for improving treatment outcomes in colorectal cancer patients, enabling breakthroughs in early diagnosis and treatment, and providing patients with more personalized, precise, and effective treatment strategies.

ADP-Ribosylation Factor 6 Pathway Acts as a Key Executor of Mesenchymal Tumor Plasticity

Despite the "big data" on cancer from recent breakthroughs in high-throughput technology and the development of new therapeutic modalities, it remains unclear as to how intra-tumor heterogeneity and phenotypic plasticity created by various somatic abnormalities and epigenetic and metabolic adaptations orchestrate therapy resistance, immune evasiveness, and metastatic ability. Tumors are formed by various cells, including immune cells, cancer-associated fibroblasts, and endothelial cells, and their tumor microenvironment (TME) plays a crucial role in malignant tumor progression and responses to therapy. ADP-ribosylation factor 6 (ARF6) and AMAP1 are often overexpressed in cancers, which statistically correlates with poor outcomes. The ARF6-AMAP1 pathway promotes the intracellular dynamics and cell-surface expression of various proteins. This pathway is also a major target for KRAS/TP53 mutations to cooperatively promote malignancy in pancreatic ductal adenocarcinoma (PDAC), and is closely associated with immune evasion. Additionally, this pathway is important in angiogenesis, acidosis, and fibrosis associated with tumor malignancy in the TME, and its inhibition in PDAC cells results in therapeutic synergy with an anti-PD-1 antibody in vivo. Thus, the ARF6-based pathway affects the TME and the intrinsic function of tumors, leading to malignancy. Here, we discuss the potential mechanisms of this ARF6-based pathway in tumorigenesis, and novel therapeutic strategies.

CMTM6 as a potential therapy target is associated with immunological tumor microenvironment and can promote migration and invasion in pancreatic adenocarcinoma

CMTM6 has been connected to the development of several malignancies. However, it is still unknown what function CMTM6 serves in pancreatic adenocarcinoma (PAAD). We obtained RNA sequencing information of PAAD from public datasets and predicted statistical significance of CMTM6 survival in accordance with Kaplan-Meier curves. Gene set enrichment assessment (GSEA) was employed to analyze changes in pathways. Then, we systematically investigated the association involving CMTM6 and the immunological traits within the tumor microenvironment (TME) of PAAD, including immune pathways, immunomodulators, immune infiltrating cells, inflammatory activities, and immunotherapy response prediction. To demonstrate the biologically malignant properties of CMTM6 expression, the Cell Counting Kit-8, transwell experiments, colony formation, and wound healing were utilized. Upregulated CMTM6 expression was revealed within PAAD tissues, which was associated with more frequent somatic mutations and worse survival outcomes. Specifically, CMTM6 expression represented stronger immune infiltration, inflammatory activity, and better immunotherapeutic response in TME. Functional studies revealed that CMTM6 promoted the ability to proliferate, migrate, and invade. Additionally, CMTM6 and PD-L1 had a positive relationship, and CMTM6 can co-immunocoprecipitate with PD-L1 protein in pancreatic cell lines. CMTM6 overexpression shapes the inflammatory TME with a strong immune response. These findings support that CMTM6 is an immunotherapeutic target with promising effect to treat PAAD.

Tumor stroma Siglec15 expression is a poor prognosis predictor in colon adenocarcinoma

Sialic acid binding Ig-like lectin 15 (Siglec15) is considered a novel immune checkpoint and an emerging target for next-generation cancer immunotherapy. However, the significance of Siglec15 and its relationship with programmed death-ligand 1 (PD-L1) in colon adenocarcinoma (COAD) remain unknown. In this study, we analyzed Siglec15 expression within stromal area (SA) and tumor area (TA), and its relationship with tumor-infiltrating lymphocytes (TILs) in COAD and mismatch repair-proficient (MMR-p) COAD. Siglec15 expression was significantly higher in COAD tissues than in normal tissues, and elevated Siglec15(SA) expression, rather than Siglec15(TA) and Siglec15 (whole) expression, was correlated with poor prognosis and inversely correlated with the density of CD8+ T cell, both in COAD and MMR-p COAD. Moreover, there were no correlations between Siglec15(SA) and PD-L1(SA), and between Siglec15(TA) and PD-L1(TA), whereas there was positive correlation between Siglec15(whole) and PD-L1(whole). A new immune classification based on the Siglec15(SA)/PD-L1(SA) expression, indicated that patients with Siglec15(SA)Low/PD-L1(SA)+ status had the longest survival times in COAD. Our study highlights that Siglec15(SA) is an independent predictor of poor prognosis and has an immunosuppressive role in COAD and MMR-p COAD tissues. These findings may provide insights into improving responses to immunotherapy-included comprehensive treatments for COAD in the future.

The CD58-CD2 axis is co-regulated with PD-L1 via CMTM6 and shapes anti-tumor immunity

The cell-autonomous balance of immune-inhibitory and -stimulatory signals is a critical process in cancer immune evasion. Using patient-derived co-cultures, humanized mouse models, and single-cell RNA-sequencing of patient melanomas biopsied before and on immune checkpoint blockade, we find that intact cancer cell-intrinsic expression of CD58 and ligation to CD2 is required for anti-tumor immunity and is predictive of treatment response. Defects in this axis promote immune evasion through diminished T cell activation, impaired intratumoral T cell infiltration and proliferation, and concurrently increased PD-L1 protein stabilization. Through CRISPR-Cas9 and proteomics screens, we identify and validate CMTM6 as critical for CD58 stability and upregulation of PD-L1 upon CD58 loss. Competition between CD58 and PD-L1 for CMTM6 binding determines their rate of endosomal recycling over lysosomal degradation. Overall, we describe an underappreciated yet critical axis of cancer immunity and provide a molecular basis for how cancer cells balance immune inhibitory and stimulatory cues.

Prognostic significance and immune correlates of FADD in penile squamous cell carcinoma

Penile squamous cell carcinoma (PSCC) with a poor prognosis lacks reliable biomarkers for stratifying patients. Fas-associated death domain (FADD) could regulate cell proliferation and has shown promising diagnostic and prognostic significance in multiple cancers. However, researchers have not determined how FADD exerts its effect on PSCC. In this study, we set out to investigate the clinical features of FADD and the prognostic impact of PSCC. Additionally, we also assessed the role of affecting the immune environment in PSCC. Immunohistochemistry was carried out to evaluate the protein expression of FADD. The difference between FADD^high and FADD^low was explored by RNA sequencing from available cases. The immune environment evaluation of CD4, CD8, and Foxp3 was performed by immunohistochemical. In this study, we found that FADD was overexpressed in 19.6 (39/199) patients, and the overexpression of FADD was associated with phimosis (p=0.007), N stage (p<0.001), clinical stage (p=0.001), and histologic grade (p=0.005). The overexpression of FADD was an independent prognostic factor for both PFS (HR 3.976, 95% CI 2.413-6.553, p<0.001) and OS (HR 4.134, 95% CI 2.358-7.247, p<0.001). In addition, overexpression of FADD was mainly linked to T cell activation and PD-L1 expression combined with PD-L1 checkpoint in cancer. Further validation demonstrated that overexpression of FADD was positively correlated with the infiltration of Foxp3 in PSCC (p=0.0142). It is the first time to show that overexpression of FADD is an adjunct biomarker with poor prognosis in PSCC and could also serve as a tumor immune environment regulator.

CKLF as a Prognostic Biomarker and Its Association with Immune Infiltration in Hepatocellular Carcinoma

The Chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing (CMTM) family, comprising nine members, is involved in the tumorigenesis and progression of various cancers. However, the expression profiles and clinical significance of CMTM family members in hepatocellular carcinoma (HCC) are not fully clarified. In this study, the RNA-sequencing and clinical data were downloaded from The Cancer Genome Atlas (TCGA) databases. The Kaplan–Meier method and the Cox proportional hazards regression analysis were used to evaluate the prognostic significance of CMTM family members. Single-sample gene set enrichment analysis (ssGSEA) and ESTIMATE algorithms were employed to explore the relationship between CMTM family genes and the tumor microenvironment in HCC. Finally, the prognostic CMTM family gene expression was further validated by quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemical (IHC) staining in clinical HCC tissue specimens. The results indicated that, compared with normal tissues, the expression of CKLF, CMTM1, CMTM3, CMTM4, CMTM7, and CMTM8 were significantly upregulated in HCC, while the expression of CMTM2, CMTM5, and CMTM6 were significantly downregulated in HCC. Univariate and multivariate Cox regression analysis demonstrated that CKLF was an independent prognostic biomarker for the overall survival (OS) of HCC patients. In HCC, the expression of CKLF was found to be correlated with immune cell infiltration, immune-related functions, and immune checkpoint genes. The qRT-PCR and IHC confirmed that CKLF was highly expressed in HCC. Overall, this research suggested that CKLF is involved in immune cell infiltration and may serve as a critical prognostic biomarker, which provides new light on the therapeutics for HCC.

Suppression of Tumor or Host Intrinsic CMTM6 Drives Antitumor Cytotoxicity in a PD-L1-Independent Manner

CKLF-like MARVEL transmembrane domain-containing protein 6 (CMTM6) is known to be a regulator of membranal programmed death ligand 1 (PD-L1) stability and a factor associated with malignancy progression, but the effects and mechanisms of CMTM6 on tumor growth, as well as its potential as a target for therapy, are still largely unknown. Here, we show that CMTM6 expression increased with tumor progression in both patients and mice. Ablation of CMTM6 significantly reduced human and murine tumor growth in a manner dependent on T-cell immunity. Tumor CMTM6 suppression broke resistance to immune-checkpoint inhibitors and remodeled the tumor immune microenvironment, as specific antitumor cytotoxicity was enhanced and contributed primarily to tumor inhibition. Without the PD-1/PD-L1 axis, CMTM6 suppression still significantly dampened tumor growth dependent on cytotoxic cells. Furthermore, we identified that CMTM6 was widely expressed on immune cells. T-cell CMTM6 levels increased with sustained immune activation and intratumoral immune exhaustion and affected T cell-intrinsic PD-L1 levels. Host CMTM6 knockout significantly restrained tumor growth in a manner dependent on CD8+ T cells and not entirely dependent on PD-L1. Thus, we developed and evaluated the antitumor efficacy of CMTM6-targeting adeno-associated virus (AAV), which effectively mobilized antitumor immunity and could be combined with various antitumor drugs. Our findings reveal that both tumor and host CMTM6 are involved in antitumor immunity with or without the PD-1/PD-L1 axis and that gene therapy targeting CMTM6 is a promising strategy for cancer immunotherapy.

[Advances in the Study of Chemokine-like Factor Superfamily Members in Tumors]

Chemokine-like factor-like MARVEL transmembrane domain containing member/chemokine-like factor superfamily member (CMTM/CKLFSF) including CKLF and CMTM1-CMTM8 are a new family of proteins linking chemokines and transmembrane superfamilies. CMTM not only have broad chemotactic activities, but also associate with hematopoietic system, immune system, and tumor development and metastasis closely. CMTM proteins are involved in key biological processes of cancer development, which include activation and recycling of growth factor receptors, cell proliferation and metastasis, and regulation of the tumor immune microenvironment. This is a new focus of research on the relationship between CMTM and tumors, because CMTM4/CMTM6 can be considered as a regulator for programmed cell death ligand 1 (PD-L1). This paper reviews the role of CMTM family members on cancer, especially in tumor growth, metastasis and immune escape, summarize the latest findings on the relationship between CMTM and non-small cell lung cancer, and explores the potential clinical value of CMTM as a novel drug target or biomarker.
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CMTM6 is highly expressed in lung adenocarcinoma and can be used as a biomarker of a poor diagnosis

Background

CMTM6 which is chemokine-like factor (CKLF)-like Marvel transmembrane domain containing family member 6 is involved in the occurrence and progression of various tumors. However, the role of CMTM6 is still unclear in lung adenocarcinoma (LUAD).

Methods

Immunohistochemical, Western blotting and RT‒PCR methods were used to detect the expression of CMTM6 in LUAD. Cox regression and the Kaplan‒Meier method were performed to assess overall survival. Immunogenic features were evaluated according to immune cell infiltrations, immune checkpoints. The sensitivity to chemotherapy agents was estimated using the pRRophetic package.

Results

In LUAD, the expression of CMTM6 was obviously upregulated and was significantly associated with T stage (p = 0.008) and lymph node metastasis (p = 0.018). Multivariate Cox regression analysis demonstrated that CMTM6 was a specialty prognostic risk factor. Based on GSEA enrichment analysis, we found that high expression of CMTM6 is associated with multiple immune signaling pathways. The group with high CMTM6 expression showed a positive association with various types of tumor-infiltrating cells. Moreover, a total of 36 chemotherapeutic drugs were significantly correlated with the expression of CMTM6. Among them, two chemotherapeutic drugs had better therapeutic effects in the high CMTM6 expression group, while 34 chemotherapeutic drugs had therapeutic effects in the low CMTM6 expression group.

Conclusion

This study confirmed that CMTM6 is highly expressed in LUAD and is a new independent poor prognostic factor. In addition, the high expression of CMTM6 is closely related to the tumor microenvironment and immunotherapy, providing new ideas for the treatment of posterior LUAD.

Chemokine-like factor-like MARVEL transmembrane domain containing 6: Bioinformatics and experiments in vitro analyze in glioblastoma multiforme

Introduction

Chemokine-like factor (CKLF)-like MARVEL transmembrane domain containing 6 (CMTM6) is a protein localized to the cell membrane and is known for its ability to co-localize with PD-L1 on the plasma membrane, prevent PD-L1 degradation, and maintain PD-L1 expression on the cell membrane. CMTM6 is highly expressed and plays an important role in various tumors such as oral squamous cell carcinoma (OSCC) and colorectal cancer (CRC), however, its role in Glioblastoma multiforme (GBM) is unclear.

Methods

In this paper, to investigate the role of CMTM6 in GBM, we analyzed the expression of CMTM6 in GBM, the interaction with CMTM6 and the associated genes by bioinformatics. Importantly, we analyzed the expression of CMTM6 in GBM in relation to tumor-infiltrating lymphocytes (TILs), immunoinhibitors, immunostimulators, chemokines and chemokine receptors. We further analyzed the function of CMTM6 and performed in vitro experiments to verify it. Finally, the sensitivity of CMTM6 to drugs was also analyzed and the relationship between CMTM6 and the anticancer drug Piperlonguminine (PL) was verified in vitro.

Results

The results showed that CMTM6 was highly expressed in GBM and correlated with multiple genes. Furthermore, CMTM6 is closely related to the immune microenvironment and inflammatory response in GBM. Bioinformatic analysis of CMTM6 correlated with the function of GBM, and our experiments demonstrated that CMTM6 significantly promoted the migration of GBM cells and epithelial-mesenchymal transition (EMT), but had no significant effect on other functions. Interestingly, we found that in GBM, PL promotes the expression of CMTM6.

Discussion

In this paper, we have performed a detailed analysis and validation of the role of CMTM6 in GBM using bioinformatics analysis and in vitro experiments to demonstrate that CMTM6 may be a potential target for glioma therapy.

Prognostic value of programmed cell death ligand 1 expression in patients with intrahepatic cholangiocarcinoma: a meta-analysis

Background

Programmed cell death ligand 1 (PD-L1) is highly expressed in intrahepatic cholangiocarcinoma (ICC) tissues. But there is still a dispute over the prognostic value of PD-L1 in patients with ICC. This study aimed to evaluate the prognostic value of PD-L1 expression in patients with ICC.

Methods

We performed a meta-analysis based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Guidelines. We searched the literature from PubMed, Embase, Web of Science, and the Cochrane Library up to December 5, 2022. Hazard ratios (HR) and their 95% confidence intervals (95% CI) were calculated to analyze the overall survival (OS), recurrence-free survival (RFS), and time to relapse. The quality of the studies was assessed using the Newcastle-Ottawa scale. Publication bias was assessed using a funnel plot and Egger's test.

Results

Ten trials with 1944 cases were included in this meta-analysis. The results showed that the low-PD-L1 group had a statistically significant advantage in OS (HR, 1.57; 95% CI, 1.38-1.79, P <0.00001), RFS (HR, 1.62; 95% CI, 1.34-1.97, P <0.00001), and time to relapse (HR, 1.60; 95% CI, 1.25-2.05, P = 0.0002) compared with the high-PD-L1 group. High programmed cell death (PD1)levels, on the other hand, were correlated with poorer OS (HR, 1.96; 95% CI, 1.43-2.70; P <0.0001) and RFS (HR, 1.87; 95% CI, 1.21-2.91; P = 0.005). Multivariate analysis showed that PD-L1 could act as an independent predictor for OS (HR, 1.48; 95% CI, 1.14-1.91; P = 0.003) and RFS (HR, 1.74; 95% CI, 1.22-2.47; P = 0.002), and PD1 acted as an independent predictor for OS (HR, 1.66; 95% CI, 1.15-2.38; P = 0.006).

Conclusion

This meta-analysis demonstrated that high PD-L1/PD1 expression is associated with poor survival in ICC. PD-L1/PD1 may be a valuable prognostic and predictive biomarker and potential therapeutic target in ICC.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022380093.

CMTM7 recognizes an immune-hot tumor microenvironment and predicts therapeutic response of immunotherapy in breast cancer well

Breast cancer (BRCA) is a complex disease that leads to major mortalities and unsatisfactory clinical outcomes among women worldwide. CKLF-like MARVEL transmembrane domain-containing 7 (CMTM7) is a potential tumor suppressor and regulator of PD-L1, which has been found as a functional signature in considerable oncogenesis, progression, and therapeutic resistance via deletion and downregulation. In this research, triple-negative breast cancer (BRCA), a molecular subtype having a lower response to endocrinotherapy but a higher response to chemotherapy and immunotherapy, showed higher transcriptional levels of CMTM7. Moreover, CMTM7 positively correlated with immunomodulators, tumor-infiltrating immune cells (TIICs), and immune checkpoints in many independent datasets. Furthermore, in an immunotherapy cohort of BRCA, patients with high CMTM7 expression were more sensitive to immunotherapy, and the therapeutic predictive value of CMTM7 is higher than that of PD-1 and PD-L1. To sum up, CMTM7 correlated with an inflamed tumor microenvironment and identified immune-hot tumors, which can be a novel biomarker for the recognition of immunological characteristics and an immunotherapeutic response in BRCA.

Predictive biomarkers of colon cancer immunotherapy: Present and future

Immunotherapy has revolutionized colon cancer treatment. Immune checkpoint inhibitors (ICIs) have shown clinical benefits for colon cancer patients, especially those with high microsatellite instability (MSI-H). In 2020, the US Food and Drug Administration (FDA)-approved ICI pembrolizumab as the first-line treatment for metastatic MSI-H colon cancer patients. Additionally, neoadjuvant immunotherapy has presented efficacy in treating early-stage colon cancer patients. Although MSI has been thought of as an effective predictive biomarker for colon cancer immunotherapy, only a small proportion of colon cancer patients were MSI-H, and certain colon cancer patients with MSI-H presented intrinsic or acquired resistance to immunotherapy. Thus, further search for predictive biomarkers to stratify patients is meaningful in colon cancer immunotherapy. Except for MSI, other biomarkers, such as PD-L1 expression level, tumor mutation burden (TMB), tumor-infiltrating lymphocytes (TILs), certain gut microbiota, ctDNA, and circulating immune cells were also proposed to be correlated with patient survival and ICI efficacy in some colon cancer clinical studies. Moreover, developing new diagnostic techniques helps identify accurate predictive biomarkers for colon cancer immunotherapy. In this review, we outline the reported predictive biomarkers in colon cancer immunotherapy and further discuss the prospects of technological changes for biomarker development in colon cancer immunotherapy.

Prognostic significance and immune characteristics of CMTM4 in hepatocellular carcinoma

Background

Previous study has shown that chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing family member 4 (CMTM4) can bind and maintain programmed cell death ligand 1 (PD-L1) expression to promote tumor progression by alleviating the suppression of tumor-specific T cell activity, suggesting its potential role in tumor immunotherapy. However, the role of CMTM4 in tumor immunity has not been well clarified, especially in hepatocellular carcinoma (HCC).

Methods

The protein expression of CMTM4/PD-L1/CD4/CD8 was detected by immunohistochemistry (IHC) detection in 90 cases of HCC tissues. The mRNA expression profiles and related prognosis data were obtained from The Cancer Genome Atlas-Liver Hepatocellular Carcinoma (TCGA-LIHC). Two immune therapy cohorts were from Imvigor210 and GSE176307.

Results

Though the single protein expression of CMTM4, PD-L1, CD4 or CD8 in HCC tissues by IHC detection didn’t show a significant relationship with the prognosis of HCC patients, we found that high co-expression of CMTM4/PD-L1/CD4 showed a good prognosis of HCC patients. Further Timer 2.0 analysis identified that HCC patients with high expression of CMTM4/PD-L1 and high infiltration of CD4⁺ T cells had a better overall survival than those with low infiltration of CD4⁺ T cells. Moreover, a series of bioinformatics analyses revealed that CMTM4-related genes posed important effects on prognosis and immunity in HCC patients, and CMTM4 had a positive correlation with infiltration of CD4⁺ and CD8⁺ T cells in HCC. At last, we used two immunotherapy cohorts to verify that the combination of CMTM4 with PD-L1 could improve the prognosis of tumor patients underwent immunotherapy.

Conclusions

CMTM4 and PD-L1 co-expression with T cell infiltration shows prognostic significance in HCC, suggesting combined effect from multiple proteins should be considered in HCC treatment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09999-y.

CMTM6 and CMTM4 as two novel regulators of PD-L1 modulate the tumor microenvironment

The tumor microenvironment (TME) plays crucial roles in regulating tumor occurrence, progress, metastasis and drug resistance. However, it remains largely elusive how the components of TME are regulated to govern its functions in tumor biology. Here, we discussed how the two novel functional proteins, chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing 6 (CMTM6) and CMTM4, which involved in the post-translational regulation of PD-L1, modulate the TME functions. The roles of CMTM6 and CMTM4 in regulating TME components, including immune cells and tumor cells themselves were discussed in this review. The potential clinical applications of CMTM6 and CMTM4 as biomarkers to predict therapy efficacy and as new or combined immunotherapy targets are also highlighted. Finally, the current hot topics for the biological function of CMTM6/4 and several significant research directions for CMTM6/4 are also briefly summarized in the review.

Lack of Association Between PDCD-1 Polymorphisms and Colorectal Cancer Risk: A Case-Control Study

Functional variants of immune-related genes may be implicated in the occurrence of colorectal cancer (CRC). In this study, Programmed cell death (PDCD)-1.6 (rs10204525 T/C), PDCD-1.7 (rs7421861 A/G), and PDCD-1.9 (rs2227982 A/G) loci were selected to explore gene expression and the potential susceptibility to the development of CRC. Here, 1,003 CRC patients and 1,303 controls were included and three PDCD-1 tagging loci were selected and analyzed by using SNPscan genotyping assays. SHESIS software was harnessed to obtain the haplotypes of the PDCD-1 gene. We found that the genotype and allele distribution of PDCD-1 tagging loci did not significantly affect the risk of CRC. Adjustment for body mass index, age, smoking, alcohol using and sex also found that PDCD-1 tagging loci did not influence the occurrence of CRC. In conclusion, this study suggests that the PDCD-1 tagging loci (rs10204525, rs7421861, and rs2227982) are not correlated with CRC susceptibility.

CMTM Family and Gastrointestinal Tract Cancers: A Comprehensive Review

Gastrointestinal tract cancers are a highly heterogeneous group of malignant diseases, contributing significantly to the burden of death worldwide. Chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing family (CMTMs) plays important roles in cancer development and progression. Since the first member was cloned, there have been abundant studies on the relationships between the CMTM family and human cancers. It has been reported that the CMTM family has a large potential prognostic value for multiple cancers. Meanwhile, upregulated or downregulated expression of the family members was related to advanced tumor stage, metastasis, and overall survival. Studies have also reported that these proteins play critical roles in antitumor immunity. We performed a systematic review to sum up the latest advances of CMTM family’ roles in gastrointestinal tract cancers, with a primary focus on hepatocellular carcinoma and gastric carcinoma.

The clinical and prognostic significance of CMTM6/PD-L1 in oncology

The recent discovery of CMTM6 and to a lesser extent CMTM4, two members of the chemokine-like factor (CKLF)-like MARVEL transmembrane domain-containing family, as master positive regulators of PD-L1 expression, the primary ligand of programmed cell death 1 (PD-1), on tumor and immune cells has opened new horizons for investigating the role of CMTM6/CMTM4 in different aspects of oncology including their clinical and prognostic values in different cancer types. The absence of a specific review article addressing the available results about the clinical and prognostic roles of CMTM6 alone and/or in combination with PD-L1 in cancer has encouraged us to write this paper.

DFNA5 regulates immune cells infiltration and exhaustion

Background

DFNA5 (GSDME) belongs to Gasdermin familily that is involved in a variety of cancers and triggers cell pyroptosis after chemical treatment. However, the relationship in DFNA5 between prognosis and immune cells in diverse cancers has been receiving little attention. Tumor immune cells infiltration and exhaustion may associate with patients prognosis. The roles of DFNA5 in tumor immune cells infiltration and exhaustion have not been clarified.

Methods

The expression level of DFNA5 was determined by the Tumour Immune Estimation Resource and the Oncomine database. Then the impacts of DFNA5 in prognosis were assessed by Kaplan–Meier plotter and ULACAN. The correlations between DFNA5 and tumour-infiltrating lymphocytes were explored by TIMER. In addition, the relationships in the expression levels of DFNA5 and typical genes combination of tumour-infiltrating lymphocytes were analysed by GEPIA and TIMER. In this study, we screened the chemokine and immune related proteins interacted with DFNA5 using TurboID system to explore the instantaneous or weak interactions.

Results

DFNA5 significantly influences the prognosis in different cancers according to The Cancer Genome Atlas (TCGA). The expression levels of DFNA5 showed positive correlations to the infiltration of macrophages, CD8 + T cells, CD4 + T cells in liver hepatocellular carcinoma (LIHC), colon adenocarcinoma (COAD), and lung adenocarcinoma (LUAD). DFNA5 expression displayed obvious correlations with multiple lymphocytes gene makers in COAD, LIHC and LUAD. DFNA5 expression has effects on the prognosis of liver hepatocellular carcinoma and LUAD. DFNA5 upregulated the expression levels of PDCD1 and CD274 in a dose-dependent manner. Chemokine and immune related proteins interact with DFNA5.

Conclusions

These results indicate that DFNA5 is related to patient prognosis and immune cells, consisting of macrophages, CD4 + T cells, and CD8 + T cells, in diverse cancers. In addition, DFNA5 expression might contribute to the regulation of T cell exhaustion, tumour-associated macrophages (TAMs), and Tregs in COAD, LIHC and LUAD. DFNA5 may regulate immune infiltration via EIF2AK2. IFNGR1 was related to the functions of PD-L1 expression and PD-1 checkpoint pathway. These results indicate that DFNA5 levels may be act as a prognostic factor and predict the degrees of immune cells infiltration in LIHC and LUAD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02487-0.

CMTM6 inhibits tumor growth and reverses chemoresistance by preventing ubiquitination of p21 in hepatocellular carcinoma

Hepatocellular carcinoma is one of the most common malignancies and has a poor prognosis. The ubiquitin-proteasome pathway is required for the degradation of most short-lived proteins. CMTM6 has been implicated in the progression of various tumors, but its biological function and the underlying molecular mechanisms in HCC are still unknown. In this study, we found that the expression of CMTM6 was significantly reduced in HCC and predicted better prognosis of HCC patients. Through in vitro and in vivo experiments, CMTM6 was shown to inhibit the proliferation of HCC cells by blocking the G1/S phase transition. Mechanistically, CMTM6 interacted with p21 and prevented its ubiquitination mediated by SCFSKP2, CRL4CDT2 and APC/CCDC20 in a cell-cycle–independent manner. As a result, CMTM6 stabilized p21 protein, leading to the inactivation of pRB/E2F pathway. Additionally, CMTM6 sensitized HCC cells to doxorubicin and cisplatin, positively correlated with better clinical outcomes of the transarterial chemoembolization (TACE) treatment for postoperative recurrence. Taken together, our study reports a novel mechanism by which p21 can be stabilized by CMTM6 and pinpoints a crucial role of the CMTM6-p21 axis in suppressing the progression of HCC and sensitizing patients with postoperative recurrence to TACE treatment.

Loss of CMTM6 promotes DNA damage-induced cellular senescence and antitumor immunity

Recent studies have revealed that chemokine-like factor-like MARVEL transmembrane domain-containing family member 6 (CMTM6) promotes tumor progression and modulates tumor immunity by regulating programmed death-ligand 1 stability; however, its intrinsic functions and regulatory mechanisms in clear cell renal cell carcinoma (ccRCC) remain poorly understood. Here, we show that CMTM6 is upregulated in ccRCC tissues and is strongly associated with advanced tumor grades, early metastases, and a worse prognosis. CMTM6 depletion significantly impaired the proliferation, migration, and invasion of ccRCC cells in vitro and in xenograft mouse models in vivo. In addition, targeting CMTM6 promotes anti-tumor immunity, represented by increased infiltration of CD4⁺ and CD8⁺ T cells in syngeneic graft mouse models. Further research revealed that loss of CMTM6 triggered aberrant activation of DNA damage response, resulting in micronucleus formation and G2/M checkpoint arrest, finally leading to cellular senescence with robust upregulation of numerous chemokines and cytokines. Our findings show for the first time the novel role of CMTM6 in maintaining cancer genome stability and facilitating tumor-mediated immunosuppression, linking DNA damage signaling to the secretion of inflammatory factors. Targeting CMTM6 may improve the treatment of patients with advanced ccRCC.

CMTM6, a potential immunotherapy target

The CKLF-like MARVEL transmembrane domain-containing protein 6 (CMTM6), which binds to the programmed death ligand 1 (PD-L1) and stabilizes the expression of PD-L1 on the cell surface, has been recently discovered as a novel regulator of PD-L1 expression in cancer. PD-L1 is an immune checkpoint inhibitory molecule that can mediate the immune escape of tumor cells in various tumors and has been studied intensively in recent years. In 2017, two articles simultaneously reported that CMTM6 can stabilize the expression of PD-L1 on the plasma membrane and prevent PD-L1 from being degraded by lysosomes; therefore, CMTM6 may play an important role in tumor cell immune escape and immunosuppression. At present, there are few studies on the relationship between the expression of CMTM6 and PD-L1 in different tumors and diseases. These studies together suggested that CMTM6 may be a potential novel immunotherapy target. In this review, we briefly describe the latest research progresses of CMTM6 in various cancers and other diseases.

Co-Expression with Membrane CMTM6/4 on Tumor Epithelium Enhances the Prediction Value of PD-L1 on Anti-PD-1/L1 Therapeutic Efficacy in Gastric Adenocarcinoma

Simple Summary

Immunotherapeutic efficacy is low even in PD-L1 positive patients with advanced gastric adenocarcinoma. Based on the results of 6-color multiplex immunofluorescence staining of the gastric tumor tissues in tissue array and 48-case pre-immunotherapy patients, a better prognostic value was found in the membrane co-expression of CMTM6/4 and PD-L1 in tumor epithelial cells than PD-L1 alone. The membrane co-expression of CMTM6/4 and PD-L1 can be used as a valuable tool for precision pre-immunotherapy patient screening in gastric adenocarcinoma.

Abstract

Anti-PD-1/L1 immunotherapy has been intensively used in heavily treated population with advanced gastric adenocarcinoma. However, the immunotherapeutic efficacy is low even in PD-L1 positive patients. We aimed to establish a new strategy based on the co-expression of CMTM6/4 and PD-L1 for patient stratification before immunotherapy. By analyzing the data obtained from TCGA and single-cell RNA sequencing at the mRNA level, and 6-color multiplex immunofluorescence staining of tumor tissues in tissue array and 48-case pre-immunotherapy patients at the protein level, we found that CMTM6/4 and PD-L1 co-expressed in both epithelial and mesenchymal regions of gastric adenocarcinoma. The tumor tissues had higher levels of CMTM6/4 expression than their adjacent ones. A positive correlation was found between the expression of CMTM6/4 and the expression of PD-L1 in tumor epithelium. Epithelial co-expression of CMTM6/4 and PD-L1 in gastric tumor region was associated with shorter overall survival but better short-term response to anti-PD-1/L1 immunotherapy. Thus, we developed a predictive model and three pathological patterns based on the membrane co-expression of CMTM6/4 and PD-L1 in tumor epithelial cells for pre-immunotherapy patient screening in gastric adenocarcinoma.

Clinical significance of PDE2A in prognosis and immune infiltration in gastrointestinal cancer based on bioinformatics analysis

BACKGROUND

Gastrointestinal cancer is one of the most common malignant cancers, but its prognosis is still poor. Exploring potential biomarkers is an important aspect of cancer research. We intended to explore potential biomarkers for gastrointestinal cancer using bioinformatics methods.

AIM

To explore the correlation between the expression of PDE2A and immune infiltration in gastrointestinal cancer, and to investigate the prognostic value of PDE2A in gastrointestinal cancer.

METHODS

The mRNA and protein expression of PDE2A in different gastrointestinal cancers was analyzed based on the HPA, TIMER, and UALCAN databases. GEPIA database was used to investigate the effect of PDE2A on prognosis of patients with different gastrointestinal cancers. The relationship between PDE2A expression and immune infiltration was analyzed using the TIMER database. Frequencies of PDE2A mutations were analyzed using cBioPortal database. Protein-protein interaction network analysis of PDE2A was based on the STRING database.

RESULTS

The mRNA and protein expression of PDE2A in liver hepatocellular carcinoma (LIHC), stomach adenocarcinoma (STAD), pancreatic adenocarcinoma (PAAD), colon adenocarcinoma (COAD), and esophageal carcinoma (ESCA) was lower than that in normal adjacent tissues. Patients with LIHC and PAAD with high PDE2A expression had a better prognosis. The expression of PDE2A was positively or negatively correlated with different immune cells such as CD4+ T cells, CD8+ T cells, B cells, macrophages, and neutrophils in LIHC, STAD, PAAD, COAD, and ESCA. Finally, there were missense mutations in PDE2A gene in STAD, PAAD, COAD, and ESCA.

CONCLUSION

The expression of PDE2A is related to immune infiltration in gastrointestinal cancer. Patients with LIHC and PAAD with high PDE2A expression have a better prognosis. PDE2A may be a potential immunotherapy target and prognostic marker for gastrointestinal cancer.

Interferon-induced protein 16 expression in colorectal cancer and its correlation with proliferation and immune signature markers

Interferon-induced protein 16 (IFI16) is important for innate immune recognition of foreign/damaged DNA. Abnormal IFI16 expression is closely related to the occurrence of multiple malignant tumours, but its expression pattern in colorectal cancer (CRC) remains unclear. The present study aimed to investigated IFI16 expression and association with cell proliferation in CRC tissues and adjacent normal tissues. A multiplex immunofluorescence panel of antibodies against IFI16, Ki-67 and phosphorylated (p)-ERK1/2 was applied to assess a tissue microarray (TMA). The TMA included 77 CRC samples and 74 normal adjacent tissue samples which were collected from The First People's Hospital of Yunnan Province (Kunming, China) (3 paracancerous tissues were lost because of repeated cutting). Immunohistochemistry was used to detect CD8⁺ tumour-infiltrating lymphocyte (TIL) abundance and programmed death-ligand 1 (PD-L1) expression in cancer tissues. The present study demonstrated that IFI16 localized to the nucleus of CRC cells. Although IFI16 was weakly expressed in normal mucosal epithelial cells, absent to strong expression was detectable in different patients with CRC. Typically, IFI16 was not co-localized with Ki-67 within CRC cells. The multiplex immunofluorescence data demonstrated that the proportion of IFI16^-/Ki-67⁺ cells from CRC tissues was 57.13%; however, that of IFI16⁺/Ki-67⁺ cells was 1.50%. The IFI16^-/Ki-67⁺ phenotype was significantly positively associated with the tumor-node-metastasis stage and was marginally significantly correlated with lymph node metastasis. p-ERK1/2 protein was primarily localized to the cytoplasm and cell membrane of CRC cells and sometimes to the nucleus. Although, IFI16 demonstrated a strong correlation with p-ERK1/2, IFI16 did not co-localize with p-ERK1/2 and the proportion of IFI16 and p-ERK1/2 double-negative CRC cells was 84.95%. IFI16 expression displayed no significant association with CD8⁺ TILs or PD-L1. However, a strong positive correlation between CD8⁺ TILs and PD-L1 was observed. High CD8⁺ TIL infiltration in CRC tissue was associated with lower lymph node metastasis and tumor-node-metastasis stage. In summary, the results of the present study provided a novel insight for the role of IFI16 in CRC occurrence via the regulation of cancer cell proliferation.

Programmed Death-Ligand 1 as a Regulator of Tumor Progression and Metastasis

Programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) immune checkpoint has long been implicated in modeling antitumor immunity; PD-1/PD-L1 axis inhibitors exert their antitumor effects by relieving PD-L1-mediated suppression on tumor-infiltrating T lymphocytes. However, recent studies have unveiled a distinct, tumor-intrinsic, potential role for PD-L1. In this review, we focus on tumor-intrinsic PD-L1 signaling and delve into preclinical evidence linking PD-L1 protein expression with features of epithelial-to-mesenchymal transition program, cancer stemness and known oncogenic pathways. We further summarize data from studies supporting the prognostic significance of PD-L1 in different tumor types. We show that PD-L1 may indeed have oncogenic potential and act as a regulator of tumor progression and metastasis.